1. Field of the Invention
The present invention relates to an in-vehicle pulse radar device for measuring a distance between two vehicles.
2. Description of the Related Art
In a conventional radar device, a radar reflection wave from a sailing wave that is generated on the sea when an object such as a small ship sails is detected together with a radar reflection wave from the object, a detection of the object is executed on the basis of those two radar reflection wave components. FFT means 8 subjects a digital signal stored in a corner turn memory 7 to FFT (fast Fourier transform), and estimates a Doppler frequency of the object. As a result, the radar reflection wave from the object such as the ship is separated from the radar reflection wave from the sea wave according to a difference in the Doppler frequency. This technique is disclosed in, for example, Japanese Patent Laid-Open No. 2000-321349 (pages 3 to 4, FIG. 1).
The conventional radar device leads to such a problem that it is high in the costs and a calculation period of time is long because enormous amounts of data is subjected to the FFT process, which is unsuitable for the in-vehicle device.
The present invention has been made to solve the above-mentioned problem, and therefore an object of the present invention is to provide an in-vehicle pulse radar device that reduces a signal processing load and is high in performance and inexpensive.
An in-vehicle pulse radar device according to the present invention includes: oscillation means for generating an electromagnetic wave; transmitting means for transmitting the electromagnetic wave generated by the oscillation means toward a target substance; and receiving means for receiving the reception electromagnetic wave reflected by the target substance to output data. Also, the in-vehicle pulse radar device includes signal processing means for pre-summing the data which is sampled for each of distance gates based on the data from the receiving means, and subjecting pre-summed data which is a result of the pre-summing process to an FFT process to obtain a distance between a subject vehicle and the target substance and a relative speed therebetween in accordance with a spectrum frequency and amplitude information which are a result of the FFT process.
Accordingly, since the pre-summing process is implemented prior to the FFT process, such an effect can be attained as to realize an in-vehicle radar, which can reduce the amount of FFT calculation without any deterioration of the radar detection performance, and is high in performance and inexpensive.